The invention relates to a crucible for use in connection with oxidizing melts at elevated temperatures and the method of forming the crucible.
Generally, it is known in the prior art that for melting substances having a melting point above 1,900.degree. C. only a crucible composed of graphite or a metal having a very high melting point can be considered. If the substance is an oxidizing agent or is to be melted in an oxygen containing atmosphere, the prior art teaches the use of the platinum metal iridium having a melting point of 2,454.degree. C. for the crucible material.
In the case of a substance which is an oxidizing agent or the presence of an oxidizing atmosphere, the demands on the crucible material are very great. Even a crucible of iridium can be dissolved or corroded by conventional melts so that the useful life of the crucible is greatly reduced. This problem is reflected in the high cost in the material and molding. Furthermore, the melted substance can be contaminated by the dissolved iridium.
The instant invention endeavors to eliminate many of the known disadvantages of the prior art crucibles and thereby provide an economy.